1. Technical Field
The present invention is related to a method and system to be utilized in data communications. In particular, the present invention is related to a method and system to be utilized in data communications involving at least one data communications network. Yet still more particularly, the present invention is related to a method and system, to be utilized in data communications involving at least one data communications network, and wherein said data communications involve multiple emulated data communications networks residing in the at least one data communications network, and which provide enhanced performance in communications involving multiple emulated data communications networks.
2. Description of the Related Art
Data communications is the transfer of data from one or more sources to one or more sinks that is accomplished (a) via one or more data links between the one or more sources and one or more sinks and (b) according to a protocol. Weik, Communications Standard Dictionary 203 (3rd ed. 1996). A data link is the means of connecting facilities or equipment at one location to facilities or equipment at another location for the purpose of transmitting and receiving data. Weik, Communications Standard Dictionary 206 (3rd ed. 1996). A protocol, in communications, computer, data processing, and control systems, is a set of formal conventions that govern the format and control the interactions between two communicating functional elements in order to achieve efficient and understandable communications. Weik, Communications Standard Dictionary 770 (3rd ed. 1996).
A data communications network is the interconnection of three or more communicating entities (i.e., data sources and/or sinks) over one or more data links. Weik, Communications Standard Dictionary 618 (3rd ed. 1996).
Data communications networks connect and allow communications between multiple data sources and sinks over one or more data links. The concept of a data link includes the media connecting one or more data sources to one or more data sinks, as well as the data communications equipment utilizing the media. The Data communications networks utilize protocols to control the interactions between data sources and sinks communicating over the one or more data links. Thus, it follows that such protocols must take into account the data communications requirements of data sources and links desiring communication over the one or more data links, and the nature of the underlying one or more data links themselves, in order to ensure that the requirements of such data sources and sinks are met.
Since protocols are interrelated to both the technology of the underlying data links and the data source and sink communications requirements, data communications protocols tend to evolve over time, as both data link technology and data transmission requirements change. A good example of such evolution is the relatively recent emergence of the Asynchronous Transfer Mode (ATM) protocol in order to satisfy data communications network user requirements by the use of fast digital communications equipment.
Today""s data communications network users often have widely varying data communications transmission and reception requirements over time. For example, at one point in time a user may desire to transfer computer files over a network, while at another point in time the same user may want to engage in real-time voice communications over the same network, while at yet another point in time the same user may want to transmit and receive high-resolution full motion video over the same network.
These varying user needs have greatly varying requirements as far as the underlying data networks are concerned. For example, real-time traffic such as voice and high resolution video can tolerate some loss but not delay, while non-real-time traffic such as computer data and file transfer may tolerate some delay but not loss. Furthermore, exactly when different types of traffic will occur is not known in advance, but tends to occur at random intervals. In other words, the data comes in bursts and must be transmitted at the peak rate of the burst (which may be quite high as in full motion video), but the average arrival time between bursts may be quite large and randomly distributed.
Asynchronous Transfer Mode (ATM) protocol has evolved in order to satisfy the foregoing and similar data communications requirements by use of emerging digital communications equipment. ATM is a communications protocol that (a) enables the transmission of voice, data, image, and video signals over wide area, high bandwidth communications systems; (b) provides fast packet switching in which information is inserted into small fixed size cells that are multiplexed and switched in a slotted operation, based upon header content, over a virtual circuit established immediately upon request for service; (c) has been chosen as the switching standard for broadband integrated services digital networks (BISDNs); (d) has variable transmission rates; (e) offers bandwidth on demand service, and (f) supports multiple concurrent connections over single communications lines. Weik, Communications Standard Dictionary 47 (3rd ed. 1996).
ATM is a type of fast packet switching protocol. A packet, in data communications, is a sequence of binary digits that has one or more of the following characteristics: (a) includes data, control signals, and possibly error control signals, (b) is transmitted and switched as a composite whole, (c) is arranged in a specific format, such as a header part and a data part, (d) may consist of several messages or may be part of a single message, (e) is used in asynchronous switched systems, and (f) is usually dedicated to one user for a session. Weik, Communications Standard Dictionary 690 (3rd ed. 1996). A fast packet switching protocol increases the speed of packet switching by eliminating overhead (i.e., information in a packet which is solely utilized for efficient and correct communications and has no information content of interest to the ultimate network user). Weik, Communications Standard Dictionary 690 (3rd ed. 1996). Thus, in ATM user data is divided into xe2x80x9cchunksxe2x80x9d (i.e., is xe2x80x9cpacketizedxe2x80x9d) and then control information is added to those chunks to make sure that they arrive at the appropriate destination.
In an ATM protocol network fast packet switching protocol overhead is reduced by (1) allocating flow control (making sure that a network node""s buffer capacity is not exceeded) and error control (making sure that information is not corrupted) to nodes within the network, and (2) providing different Quality of Service (with lower Quality of Services requiring less overhead) dependent upon requirements received from ATM protocol network users.
The ability of ATM to provide different Quality of Service is one of the greatest advantages of ATM. These different qualities of service allow data communications networks to carry, in an integrated way, both real-time traffic such as voice and high resolution video which can tolerate some loss but not delay, as well as non-real-time traffic such as computer data and file transfer which may tolerate some delay but not loss. Thus, ATM gives networks the ability to efficiently handle the widely variant network user data requirements referenced above.
ATM provides the mechanisms whereby widely varying user data demands may be satisfied without unduly. consuming network communications resources. That is, ATM tends to maximize efficiency of the data communication network wherein it is used. Hence, there is tremendous pressure from the communications industry to move toward ATM protocol networks.
Unfortunately for the communications industry, there exists today a tremendous installed base of non-ATM protocol networks (e.g., Wide Area Networks (WANs), Local Area Networks (LANs), Internet Protocol Networks) which do not utilize ATM protocol. Furthermore, some of the non-ATM protocol networks have features, which ATM protocol networks do not provide but that user systems have come to rely upon and have been designed to utilize. Thus, while the communications industry desires to move toward ATM protocol networks for reasons mentioned previously, a large percentage of the industry""s customer base has opposed such movement in that such customer base has previously invested in hardware and software designed for non-ATM protocol networks. Thus, a major problem faced by the industry is how to move toward ATM protocol networks without disturbing its existing installed customer base.
The communications industry has opted for an attrition strategy to solve this problem. Under this strategy, the industry has opted to move toward ATM protocol networks while simultaneously continuing to support the vast installed base of non-ATM protocol networks, and the network and link layer protocols operating on these networks. (The hope being that as new users come on line, they will utilize ATM protocol equipment and that as older systems are phased out, they will be replaced with ATM protocol systems.) The key to this strategy is empowering the ATM protocol networks to be able to support non-ATM protocols, and to be able to supply non-ATM features which users have come to expect and rely upon.
The communications industry has opted to provide such support and supply such features via various xe2x80x9coverlayxe2x80x9d schemes. While the specifics of any particular overlay implementation are complex, the general idea is relatively straightforward: any non-ATM capability will be provided by a (logically) separate protocol that is (logically) overlaid onto a base ATM protocol network. The (logically) overlaid protocol is then utilized to allow non-ATM protocol networks to interact with ATM protocol networks xe2x80x9cas ifxe2x80x9d the ATM protocol networks, and entities within such ATM protocol networks, recognize the protocols and support the features of non-ATM protocol networks.
One of the more well-known overlay schemes involves emulating the function of one network protocol scheme within the ATM network itself. An example of such is Local Area Network Emulation.
Local Area Network (LAN) Emulating protocol overlay schemes are often utilized to create one or more emulated local area networks within one or more ATM protocol networks. Each emulated network is a logical construct which is maintained by a LAN Emulation Server (the specifics of LAN Emulation Servers will be described below in the detailed description). However, from the standpoint of computing systems utilizing emulated local area networks, such emulation is completely transparent. That is, such emulation allows the use of xe2x80x9coff the shelfxe2x80x9d applications designed to function with local area network hardware and software, and functions xe2x80x9cas ifxe2x80x9d the emulated network were in fact a true, physical, local area network.
An advantage of the ATM protocol LAN emulation scheme is that it allows standard LAN hardware to be utilized, with minimal modifications, to allow communications between emulated LANs, physical LANs, or combinations of emulated and physical LANs. ATM protocol LAN emulation is able to provide such functions by providing interfaces which allow the use of virtually xe2x80x9coff the shelfxe2x80x9d physical LAN Source Route Bridges (that is, physical LAN Source Route Bridges that have been minimally modified to interface with ATM protocol LAN emulation) which are used to bridge data between the aforementioned LAN types (i.e., physical or emulated).
Such a scheme has advantages in that it allows the utilization of pre-existing equipment built for physical LANs. However, the scheme also has disadvantages in that it brings with it disadvantages inherent with using physical LAN Source Route Bridges: such LAN Source Route Bridges often serve as bottlenecks for data traffic, irrespective of the type of networks (i.e., physical or emulated). That is, just as such Source Route Bridges can serve as data bottlenecks when connecting two physical networks, the way in which ATM LAN emulation utilizes such Source Route Bridges to achieve inter-emulated LAN communication also gives rise to the same type of data bottlenecks. An example of a situation in which such a data bottleneck arises is that where there is rather continuous data traffic between a station on a first emulated LAN with a station on another emulated LAN. Another example is that where a large number of stations on a first emulated LAN linked by a Source Route Bridge to a second emulated LAN are engaging in communication with stations on the second emulated network across the Source Route Bridge.
Since all inter LAN (emulated or physical) traffic must cross the Source Route Bridge, such traffic often xe2x80x9cbacks upxe2x80x9d at the Source Route Bridge when the inter-network traffic (between either emulated, physical, or a combination of emulated and physical networks) is high. It is apparent alleviation of such data bottleneck problems is desirable. However, as was discussed above, the ATM LAN emulation""s use of physical LAN Source Route Bridges still remains desirable since it allows bridging between physical, emulated, and combinations of physical and emulated LANs.
Thus, it is apparent from the foregoing that a need exists for a method and system which retains the flexibility and power of the foregoing noted network emulation overlay schemes, and yet significantly reduces the noted data stream bottleneck problems.
It is therefore one object of the present invention to provide a method and system to be utilized in data communications.
It is therefore another object of the present invention to provide a method and system to be utilized in data communications involving at least one data communications network.
It is yet still another object of the present invention to provide a method and system, to be utilized in data communications involving at least one data communications network, and wherein said data communications involve multiple emulated data communications networks residing in the at least one data communications network, and which provide enhanced performance in communications involving multiple emulated data communications networks.
The foregoing objects are achieved as is now described. Provided are a method and system for achieving enhanced performance in communications between a plurality of emulated networks overlaid onto at least one base network, wherein the communications involve one or more source route bridges. The method and system accomplish their objects via the following. Determining when communication is to occur, through the one or more source route bridges, and between at least two entities where a first of the at least two entities is a member of a first emulated network and where a second of the at least two entities is a member of another of the plurality of emulated networks. Informing the at least one of the at least two entities of one or more addresses consonant with the protocols of the at least one base network wherein the one or more addresses identify one or more base network entities closely correspondent to at least one of the at least two entities. And thereafter, utilizing the one or more addresses in communication between the first and second entities such that communications between the first and second entities is established in such a fashion that at least one of the one or more source route bridges is bypassed, thereby ensuring that the processing and delay associated with the at least one bypassed source route bridge is avoided wherein the performance in communications involving the at least two emulated networks is enhanced.
The above as well as additional objects, features, and advantages of the present invention will become apparent in the following detailed written description.